Inflammatory responses include a broad range of host reaction to a variety of insults, such as injury, infection, or rejection. It is the over production of mediators that is believed to be associated with a broad range of disorders, including AIDS, arthritis (rheumatoid arthritis, osteoarthritis, spondyloarthropathies), antibiotic induced diarrheal diseases (Clostridium difficile), multiple sclerosis, osteoporosis, gingivitis, peptic ulcer disease, esophagitis, diabetes, retinitis, uveitis, reperfusion injury after myocardial infarction (MI), cerebral vascular accident (CVA), aphthous ulcers (oral), atherosclerosis (plaque rupture), tumor metastases, asthma, preeclampsia, and allergic disorders such as rhinitis, conjunctivitis, and urticaria.
These disorders and their symptoms are briefly summarized below. According to the methods of the present invention, IL-11 is administered to modulate the hosts' over reaction to insult thereby treating the following disorders.
Aids
Infection with HIV eventually leads to destruction of T-helper cells producing an immuno-compromised state. However, some immune cells, such as the macrophage may actually be stimulated during HIV infection. HIV-infected macrophages exhibit enhanced TNF-.alpha. production when the cells are stimulated. Excessive TNF-.alpha. production has been linked to increased pulmonary damage occurring during AIDS and has been linked to the cachexia(weight loss) which is characteristic of the disease.
Arthritis
Rheumatoid Arthritis
In rheumatoid arthritis, the synovial tissue lining the joint organizes into a mass that infiltrates and degrades articular cartilage, tendons, and bone. Normal synovial tissue consists of a thin membrane of only two or three cell layers, comprised principally of fibroblast-like synovial cells and rare resident macrophages. In contrast, rheumatoid synovial tissue consists of a mixture of cell types: immune T- and B-cells, monocyte/macrophages, polymorphonuclear leucocytes, and the fibroblast-like cells with their rampant proliferative ability. With the exception of the fibroblasts, most of these cells are recruited to the rheumatoid joint in response to inflammatory stimuli that occur as part of the pathology of this disease.
Although the etiology of rheumatoid arthritis is not clear, it is suspected that an unknown antigen, such as a bacterium, virus, or mycoplasma, is deposited in the joints as a consequence of a systemic infection. Normally, the antigen is cleared and no disease arises; however, in genetically susceptible individuals, the antigen elicits an acute inflammatory/foreign body response in which some autologous tissue damage occurs. This, in turn, develops into an (auto)immune response and eventually leads to a chronic inflammatory and immunologic reaction within the synovial lining of the joint. Thus, there is a potpourri of activated cell types, and the cytokines they produce continuously fuel the proliferative and destructive ability of the synovial fibroblasts.
Osteoarthritis
In osteoarthritis, degenerative changes to the articular cartilage, subchondral bone and the synovial membrane occur after various joints are subjected to repeated mechanical damage. Increased levels of IL-1, TNF-.alpha. and metalloproteases have been documented within the affected joints of patients.
Spondyloarthropathies
The diseases classified as spondyloarthropathy are psoriatic arthritis (PsA), juvenile chronic arthritis with late pannus onset, enterogenic spondyloarthropathies (enterogenic reactive arthritis (ReA) and inflammatory bowel diseases (IBD)), urogenital spondyloarthropathies (urogenital ReA), and the undifferentiated spondyloarthropathies.
In this type of arthridity, various types of immune mediated joint inflammation produce degenerative changes in the multiple joints. These changes consist of inflammatory infiltration within the synovial membranes and degenerative changes to the articular cartilage and the associated subchondral bone. One additional feature of this particular syndrome is that of the development of bony bridges(spondyloses) between the affected joint components. Again, increased levels of IL-1, TNF-.alpha. and metalloproteases have been documented within the affected joints of patients.
Antibiotic Induced Diarrheal Diseases
Yet another inflammatory disorder is antibiotic induced diarrheal diseases (e.g., by organisms such as Clostridium difficile). Clostridium difficile is a common cause of diarrhea and colitis in individuals receiving broad spectrum antibiotic therapy. Toxins released by the bacteria elicit an enterotoxigenic secretory diarrhea and also elicit an acute inflammatory response in the intestinal mucosa characterized by granulocyte infiltration, epithelial cell necrosis, ulceration and hemorrhagic edema.
Multiple Sclerosis
Multiple sclerosis (MS) is an inflammatory demyelinating disorder of the central nervous system (CNS). MS is characterized histopathologically by focal lesions in different stages of evolution in the white matter of the CNS. Breakdown of the blood-brain barrier and inflammatory perivascular infiltration are the first events in lesion formation and are followed by demyelination and astrogliosis. Local inflammation is most probably induced by an autoimmune response against the myelin sheath. Proteolytic enzymes are believed to contribute to the inflammatory tissue damage in this disease. Gelatinases, belonging to the matrix metalloproteases, contribute to tissue destruction in inflammatory demyelinating disorders of the central nervous system such as multiple sclerosis.
Clinical diagnosis of MS is based on the history and physical findings indicating multiple lesions in the CNS. Although some cases are progressive from the onset, most show remissions and exacerbations with lesions occurring in different places in the white matter. As in experimental allergic encephalomyelitis (EAE), the symptoms of MS vary from one individual to another and from one time to another in any particular patient. EAE is a T cell-mediated autoimmune disease of the CNS.
Immune abnormalities have been described in the peripheral blood and cerebrospinal fluid of MS patients, including the presence of inflammatory T-cells, increased synthesis of immunoregulatory cytokines, and oligoclonal immunoglobulin. Although the exact cause of MS is unknown, MS might be the consequence of auto-sensitization to myelin antigens, probably induced as cross-reactions to viral or bacterial proteins.
Osteoporosis
Postmenopausal osteoporosis is a disorder characterized by a progressive loss of bone tissue which begins after natural or surgical menopause and leads to the occurrence of spontaneous fractures. Although estrogen deficiency is known to cause bone loss by stimulating the resorptive activity of mature osteoclasts (OCs) and the proliferation and differentiation of OC precursors, the mechanism of these effects is still conjectural at best. One such mechanism may be a modulatory effect on the secretion of factors that are produced in the bone microenvironment and influence bone remodeling. Among these are IL-1, IL-6, and tumor necrosis factor .alpha. and .beta. (TNF). IL-1 and TNF promote bone resorption in vitro and in vivo by activating mature OCs indirectly, via a primary effect on osteoblasts, and by stimulating the proliferation and differentiation of OC precursors. IL-6 also increases OC formation from hemopoietic precursors. However, IL-6 does not activate mature OCs.
Gingivitis
Adult periodontitis is strongly associated with infection by Porphyromonas gingivalis. Proteolytic enzymes, which are produced in large quantity by this bacteria, are considered as important pathogenic agents. The increased production and flow of gingival crevicular fluid (GCF) is an important change in gingival tissues during periodontal infection, correlating with clinical indices of gingival inflammation. Indeed, salivary protein and albumin concentrations of individuals with periodontitis, which are an indication of plasma leakage due to vascular permeability enhancement (VPE), are significantly increased compared to healthy subjects. The production of GCF appears dependent on VPE induced at periodontitis sites, presumably involving proteinase(s) of P. gingivalis in their generation.
Peptic Ulcer Disease
Inhibition of gastric acid secretion with H.sub.2 -receptor antagonists and, more recently, blockers of H.sup.+,K.sup.+ -ATPase (also known as the proton pump) has been the mainstay of therapy for peptic ulcer disease. The pathophysiology of peptic ulcers remains obscure. An appreciation of the complexity of the physiology of the gastric mucosa has led to a hypothesis that peptic ulcers are the result of an imbalance in the relative importance of aggressive (acid, pepsin) and protective (mucus, bicarbonate, blood flow, prostaglandins, etc.) factors. Infection of the mucosa of the human gastric antrum with the bacterium Helicobacter pylori has been widely accepted as the cause of chronic, active, type B gastritis. Further, this form of gastritis has been linked directly to peptic ulcer disease by studies showing that eradication of H. pylori reverses this gastritis and prevents duodenal ulcer relapse. Because cytokines are the principal mediators by which immune/inflammatory cells communicate with each other and with other cells, it is likely that these small peptides are involved in the pathogenesis of chronic active type B gastritis and the resulting peptic ulcer disease.
Some cytokines (IL-1, epidermal growth factor, transforming growth factor-.alpha., acidic and basic fibroblast growth factors) tip the balance towards peptic ulcer healing; others (tumor necrosis factor-.alpha.) appear to have no effect; still others (IL-4) may even cause gastrointestinal damage.
Esophagitis
The most common cause of esophagitis is the chronic reflux of hydrochloric acid from the stomach due to inefficiency of the cardiac sphincter of the stomach. The chronic presence of acid in the lower esophagus leads to damage of the esophageal mucosa. In the most severe form, a syndrome called Barrett's esophagus can develop which often leads to esophageal cancer. Other causes of esophagitis include parenteral chemotherapy and ionizing radiation, associated with radiation therapy for cancer in the thoracic cavity.
Diabetes
Infiltration of the pancreatic islets by immune/inflammatory cells (insulitis), followed by loss of the insulin-producing beta cells is the characteristic histologic feature of insulin-dependent diabetes mellitus (IDDM).
IDDM is a T cell-mediated chronic autoimmune disease that is characterized by lymphocytic infiltration of the pancreatic islets of Langerhans and by the selective destruction of insulin-producing .beta. cells in the islets. Since TNF-.alpha. is a proinflammatory cytokine and its gene is localized within the major histocompatibility complex (MHC), which has been shown to have a strong genetic linkage to several autoimmune disorders including IDDM, TNF-.alpha. has been considered to be a possible candidate cytokine mediating the pathogenic destruction of .beta.-islet cells.
Retinitis
Inflammation of the light sensitive retina, retinitis, can occur due to a variety of viral, bacterial or autoimmune etiologies. The end result is destruction of the retina and loss of sight.
Uveitis
Inflammation of the anterior portion of the eye its associated structures, the iris and cornea occurs with a relatively high frequency in patients with autoimmune disorders.
Reperfusion Injury After Myocardial Infarction (MI) and Cerebral Vascular Accident (CVA)
Ischemia-induced endothelial cell injury has been described as the pivotal causative event leading to an array of pathophysiologic sequelae such as microvascular vasoconstriction, adhesion and aggregation of platelets and neutrophils, and decreased blood flow, inclusively described as the "no reflow-phenomenon" early after reperfusion.
The infiltration and activation of multiple types of inflammatory cells result in a series of degenerative changes in the vasculature of the affected area, as well as inciting damage of the surrounding parenchymal tissue.
Aphthous Ulcers (Oral)
Although the cause of aphthous ulcers remain unknown, many physicians believe they are caused by autoimmune phenomena, which cause the destruction of discrete areas of the oral mucosa which leads to oral ulceration. Among the cytokines present in these active areas of ulceration, TNF-.alpha. appears to play a predominant role.
Age-related diseases such as atherosclerosis (plaque rupture), fibrosis, osteoporosis, and many others, are associated with increased levels of certain cytokines such as IL-1, IL-6 and TNF-.alpha., suggesting that physiological aging in humans is associated with an increased capability of peripheral blood mononuclear cells to produce pro-inflammatory cytokines. Although atherosclerosis contributes to the narrowing of the blood vessel lumen, often the large atherosclerotic plaques cause fewer problems than smaller plaques. This occurs due to the sudden rupture of medium sized plaques. It appears that this rupture is associated with increased concentrations of various metalloproteases, probably derived from inflammatory cells within the plaque.
Prevention of Tumor Metastases
The processes of tumor invasion and metastasis are thought to depend upon increased proteolytic activity of invading tumor cells. Matrix metalloproteinases, cathepsins B, D, and L, and plasminogen activator have been proposed to participate in the metastatic cascade. Cathepsin D has been suggested to be an independent marker of prognosis in breast cancer.
Asthma
Asthma is a disease with two major components, a marked inflammatory reaction and a disorder of bronchial smooth muscle reactivity producing bronchospasm. Increased production of inflammatory mediators causes infiltration of leukocytes, with lymphocytes, eosinophils and mast cells being present in large quantities.
Allergic Disorders such as
Rhinitis, Conjunctivitis and Urticaria ("Hives")
In these three types of inflammation, multiple allergens are capable of evoking the infiltration and activation of "allergic" classes of leukocytes, i.e., eosinophils, mast cells and basophils, resulting in the subsequent release of histamine, platelet activating factor, etc. Given this general type of reaction, these aforementioned disorders occur in the nose, conjunctiva and the skin.
Preeclampsia
Preeclampsia is characterized by development of hypertension, endothelial cell disruption, coagulopathy, leukocyte activation, edema, renal dysfunction, and fetal growth disturbances after the twentieth week of pregnancy and occurs in 8% to 10% of all pregnancies in the United States annually. The endothelial cell damage seen in preeclampsia may be produced in part by TNF-.alpha..
It has been recently reported that IL-11 is produced by placental fibroblasts and that it causes proliferation and differentiation of the trophoblast, the major cell type of the placenta. In non-pregnant individuals, IL-11 causes a physiologic plasma volume expansion which is very similar to that caused by normal pregnancy. IL-11 also appears to be able to decrease TNF-.alpha. by activated macrophages. In preeclampsia, trophoblast growth and differentiation are abnormal, plasma volume expansion fails to occur and TNF-.alpha. levels are elevated, indirectly suggesting a deficiency of IL-11.
In Graft vs. Host Disease (GVHD), the immunologic recognition and response seen are believed to be caused by histocompatibility differences between the donor and recipient and cytotoxicity by alloreactive T cells. The cellular injury in GVHD is thought to be caused by cellular infiltration of effector cells into target tissues with resultant destruction. The theory of the destruction seen in GVHD was based on the observation of lymphocytes juxtaposed to dying cells (satellitosis) observed frequently in the skin of patients or animals with GVHD. Pulmonary complications are often lethal components of acute GVHD.